The existing ultrasonic fingerprint sensor includes a piezoelectric post array. Each piezoelectric post is corresponding to a pixel of the ultrasonic fingerprint sensor. The pixel value of the pixel corresponding to fingerprint can be detected by detecting reflected ultrasonic wave sent by each piezoelectric post to finally achieve the fingerprint recognition. The piezoelectric posts need to be processed by micro-electromechanical systems. This causes high equipment costs and complicated processes, resulting in high product cost.